1. Field of the Invention
The invention relates to a folding-top drive for actuating a motor vehicle folding top.
2. Description of the Related Art
DE 102 17 784 B4 discloses a drive device for actuating an adjustable vehicle part, such as a collapsible folding top, a hinged folding-top compartment or a luggage compartment flap. The drive device disclosed in DE 102 17 784 B4 has a gearing and a drive motor that interacts with the gearing so that the gearing transmits an actuating force of the drive motor, or an actuating moment of the drive motor, to the adjustable vehicle part to be actuated. The gearing is preferably a worm gear, and accordingly a self-locking gearing. Further drive devices for actuating a motor vehicle folding top are known from DE 38 26 411 A1 and DE 101 08 769 A1.
The drive devices or folding-top drives of the prior art have enabled a folding top of a motor vehicle to open and close. However, it has been difficult to protect a folding-top drive from overloading. Such an overloading may occur for, example, if a folding top to be opened and closed abuts against an obstruction during the opening process or closing process. Such an obstruction constitutes a resistance for the folding-top drive during the opening or closing process, and the folding-top drive then attempts to move the folding top counter to the resistance. As a result, the folding-top drive and the entire folding top can be damaged. Such damage to the folding-top drive or to the entire folding top must, however, be prevented. Furthermore, it hitherto has proven difficult to manually open or close a folding top in the event of failure of the or each drive motor of a folding-top drive. Folding-top drives that permit manual actuation of a folding top have a complex design.
It is an object of the invention to provide a novel folding-top drive that addresses the problems described above.